Objectives: Invasive candidiasis has an attributable mortality of 10-49%. It is associated with biofilm formation over indwelling devices. Biofilm-associated upregulated drug efflux makes treatment expensive and ineffective. Hence low-cost alternatives inhibiting Candidal biofilm formation are needed. Pseudomonas aeruginosa inhibits growth of Candida albicans in vitro. This study aimed to detect whether secreted products of Pseudomonas aeruginosa, especially Pyocyanin, affect biofilm production by Candida albicans and C.tropicalis. Methods: P. aeruginosa strains were incubated overnight at 37__ampersandsigndeg;C in Luria broth and centrifuged. Supernatant was filtered by syringe filter (pore size 0.22__ampersandsignmu;m). Yeast isolates were grown overnight in YPD broth (Yeast Extract-Peptone-Dextrose). Turbidity was adjusted to 106 cells/ml in YPD and culture filtrate. Then 100 __ampersandsignmu;l of both suspensions were dispensed in wells of flat-bottomed 96-well microtitre plate with normal saline as negative control. Wells were washed after incubation of 90 minutes at 37__ampersandsigndeg;C with Phosphate buffered saline (PBS) and reloaded with 100 __ampersandsignmu;l of respective liquid media. This was repeated after intervals of 24 and 48 hours. Wells were stained with 1% safranine in 95% ethanol, washed with PBS and observed under inverted microscope. Optical density was measured spectrophotometrically. Methods were repeated with filtrate, preheated at 100__ampersandsigndeg;C for 20 minutes and Pyocyanin extracted from P. aeruginosa broth culture with the help of Chloroform and acidified water. Results: Biofilm formation of Candida albicans and C. tropicalis was significantly reduced by culture filtrate, both plain and heated, and Pyocyanin. Pyocyanin was found non-toxic to host cells. Conclusions: Pyocyanin can be utilised in vivo to inhibit device-associated biofilm formation by these pathogens.